The present invention relates weft reservoir for an alternate two-pick change type fluid jet shuttleless loom, and more particularly relates to weft reservoir in which a weft continuously supplied from a given source is provisionally reserved on a rotary drum or drums for subsequent delivery to a jet nozzle on an alternate two-pick change type fluid jet shuttleless loom such as an air jet loom wherein alternate two-pick change type weft insertions are carried out within four crank cycle.
Weft reservoirs of alternate two-pick change type are classified into two categories, the one using a weft reserving tube or tubes and the other using a weft reserving drum or drums.
From the viewpoint of weft supply, they are further classified into two categories, the one employing continuous weft supply and the other employing intermittent weft supply.
Some examples of the intermittent weft supply type weft reservoir are disclosed in Japanese Patent Publication No. 10692/64 and Utility Model Publication No. 8701/73. In the case of the weft reservoir of this type, slip of weft tends to occur when weft measuring is initiated for the first weft insertion. Excessive tension may be generated on the weft at this moment, also. Further, when weft measuring for the second weft insertion comes to end, supply of weft cannot be stopped at the correct moment due to inertia of the weft and its related part, thereby disabling correct control of the measured length of the weft. In order to avoid these troubles, it is advisable to employ the continuous weft supply system.
An example of the continuous weft supply type weft reservoir is disclosed in Japanese Utility Model No. 34306/73. In the case of weft reservoir of this type, the length of weft for about two picks reserved in a weft reserving tube at one time and delivered in two separate times for weft insertion. Consequently, the length of weft reserved in the tube before the first weft insertion is different from that before the second weft insertion, i.e. after the first weft insertion. This results in a large difference in resistance against weft delivery from the tube between the first and second weft insertions. This naturally leads to difference in weft tension which ill affects the quality of the products woven on the loom for which the weft reservoir is used. During the reservation within the tube, the weft is entrained on air flow whilst forming a U-shape. This relatively free condition of the weft during the reservation tends to form kinks and/or snarls on the weft in particular when the weft is a high twist yarn, which form weaving defects on the products woven. Use of strong air stream in the tube prevents formation of such kinks and snarls on the weft during its reservation. This, however, causes other troubles such as increased resistance against weft delivery, increased power consumption and formation of fluffs. In order to avoid the above-described drawbacks, it is advantageous to use a combination of weft reservation on a drum with continuous weft supply.
In the case of the continuous weft supply system combined with reservation on a drum, however, it is necessary to subject the weft to controlled delivery during the terminal stages of the first and second weft insertions in order to avoid variance in length of the inserted weft. In the case of the conventional weft reservoirs of weft reserving drum type, it has been technically impossible to practice such a control delivery of weft during the first difficult on a conventional weft reservoir to successfully combine the weft reserving drum system with the continuous weft supply system.